Preclinical Evaluation of an Anti-CD25 Monoclonal Antibody,7G7/B6,Armed with the β-Emitter,Yttrium-90,as a Radioimmunotherapeutic Agent for Treating Lymphoma

Abstract

Objective:

Radioimmunotherapy of cancer with radiolabeled antibodies has shown promise. We evaluated an anti-CD25 monoclonal Antibody, 7G7/B6, armed with ⁹⁰Y as a potential radioimmunotherapeutic agent for CD25-expressing lymphomas.

Materials and Methods:

The lymphoma model was established by subcutaneous injection of 1 × 10⁷ SUDHL-1 cells into nude mice. The biodistribution of ¹¹¹In-7G7/B6 and therapeutic studies with ⁹⁰Y-7G7/B6 were performed in the tumor-bearing mice.

Results:

Therapy using ⁹⁰Y-7G7/B6 prolonged survival of the SUDHL-1 lymphoma-bearing mice significantly, as compared with either untreated mice or the mice treated with ⁹⁰Y-11F11, a radiolabeled isotype-matched control antibody (p < 0.001). All of the mice in the control and the ⁹⁰Y-11F11 treatment groups died by days 18 and 24, respectively. In contrast, 30% of the mice in the low-dose group (75 μCi of ⁹⁰Y-7G7/B6/mouse) and 75% in the high-dose group (150 μCi of ⁹⁰Y-7G7/B6/mouse) became tumor free and remained healthy for greater than 6 months.

Conclusions:

Our findings suggested that ⁹⁰Y-7G7/B6 is a potentially useful radioimmunotherapeutic agent for the treatment of patients with CD25-expressing lymphomas.